GitHub Copilot Adds Cross-Model 'Rubber Duck' Review — Claude Critiques GPT Sessions, GPT-5.5 Reviews Claude

GitHub Blog·high signal

GitHub expanded Copilot CLI's Rubber Duck mode with cross-family review: a Claude-powered critic for GPT sessions and GPT-5.5 second opinions for Claude sessions, designed to catch bugs, conflicts, and architectural issues that a single model family might miss. Copilot coding agent also gained dedicated 'Agents' secrets and variables at both org and repo levels, separating agent credentials from Actions configuration.